Current systems and methods of displaying information to vehicle occupants are limited to electronic (e.g., LCD, LED) displays and heads-up displays, with electronic displays predominating. Commercially available electronic displays limit the amount and quality of the displayed content, limit visibility in bright daylight and typically block visibility through the display. Heads-up displays (HUDs) are rarely used in motor vehicles. Some vehicles equipped with a HUD require a combiner (e.g., a beam splitter) located directly in front of the viewer. The combiner redirects (i.e., reflects) towards the viewer some or all of the projected image from a projector. Usually the projector is located in a dashboard, aimed upwardly. The combiner is located in front of the driver. Even while the combiner reflects the projected image towards the viewer, the viewer may see through the combiner and the window behind the combiner. Other HUD systems omit the combiner, but require a specially coated window and laser projector. In such systems, a vehicle window is coated with transparent phosphors that react (i.e., fluoresce) when impinged by projected laser light. When the laser is off, the coated window is transparent. Many such systems require mirrors to project the images on the windshield.
By way of example, one vehicle manufacturer uses windshield glass coated with red-emitting and blue-emitting phosphors—a clear synthetic material that glows when it is excited by ultraviolet light. The phosphor display is activated by ultraviolet lasers bouncing off mirrors bundled near the windshield.
While prior art display systems are useful, they have shortcomings. First, prior art HUD systems cannot be applied directly to installed windows and require costly, complex laser projectors. Second, the various available electronic displays cannot be used over a window. Transparent electronic displays, such as OLEDs, are very costly, very difficult to see in bright sunny ambient conditions, would consume considerable power to “outshine” sunlight on a bright day, and require complex interfaced dedicated display drivers.
What is needed is a means for adapting a conventional vehicle window (e.g., side window or windshield) to display images from a conventional projector that emits incoherent (i.e., non-laser) visible light, while still allowing an occupant of the vehicle to see through the adapted window. The adaptation should be suitable for existing vehicle windows.
The invention is directed to overcoming one or more of the problems and solving one or more of the needs as set forth above.